Fluid pressure seal arrangement

ABSTRACT

In a body supporting another body via a land into which sealing gas is supplied via an in-coming gas groove or grooves for liquid sealing purpose and from which fluid is discharged through a fluid groove, one or more sets of out-going gas grooves are formed opening to the land in between the in-coming gas groove(s) and the fluid groove so that both undesirable mixing of the sealing gas with the fluid and accidental invasion of outside dust or the like into the arrangement is effectively prevented.

This is a division of application Ser. No. 347,529, filed Apr. 3, 1973and now U.S. Pat. No. 3,949,996.

The present invention relates to improved static pressure sealarrangement, more particularly relates to static pressure sealarrangement for preventing outward leakage of inside fluid and inwardinvasion of outside fluid and dusts or the like via a land formedbetween a rotary shaft and its supporting bearing part or between twoconfronting surfaces.

Conventional mechanisms for sealing liquid re rotary shafts orconfronting surfaces are generally classified into two groups; one beingthe so-called contact type seals such as O-ring seals, oil seals andmechanical seals and the other being the so-called non-contact typeseals such as static pressure seals, labyrinth seals and centrifugal oilseals.

It is well known that the non-contact type seals should be employed incase friction and/or wearing-out of the seal arrangement should beobviated particularly when the same is used for rotary shafts of highspeed rotation.

However, the known non-contact type seals are accompanied by severaldisadvantages that particularly the labyrinth seals and the centrifugaloil seals are inevitably accompanied by complecated structures andinstable unbalanced rotation of the rotary shaft. Particularly, in thecase of large flow rates, there is considerable lowering in the sealingeffect.

The object of the present invention is to provide a static pressure sealarrangement of a simple structure with high sealing effect.

In order to attain this object according to the present invention, oneor more sets of out-going gas grooves are formed opening to a land,which positions between a rotary shaft and a bearing part or between twoconfronting surfaces, at positions in between in-coming gas groove(s)and fluid groove.

Further features and advantages of the present invention may be madeclearer in the following description, reference being made to theaccompanying drawings, in which;

FIG. 1 is a partly sectional vertical side plane view of theconventional static pressure seal arrangement,

FIG. 2 is a sectional top plane view of the arrangement shown in FIG. 1,

FIG. 3 is a partly sectional side plane view of a basic embodiment ofthe static pressure seal arrangement of the present invention,

FIG. 4 is a partly sectional side plane view of another embodiment ofthe static pressure seal arrangement of the present invention,

FIG. 5 is a top plane view of the other embodiment of the staticpressure seal arrangement of the present invention,

FIG. 6 is a section taken along the line VI--VI in FIG. 5.

Referring to FIGS. 1 and 2, there is shown a typical example of thestatic pressure seal arrangement of the conventional type. In thearrangement, a rotary shaft 1 is supported by a bearing part 2 in whichtwo annular grooves 3 and 4 of different diameters with respect to thelongitudinal axis of the rotary shaft 1 are formed encircling the rotaryshaft 1. A sealing gas taker-in hole 6 is formed radially through thebearing part 2 in connection with the annular groove 3 on the left sidein the drawing. The outlet part of this sealing gas taker-in hole 6 iscommunicated to pressurized supply source 15 containing of the sealinggas via a pressure regulating valve 7. Separately from this, a fluiddischarge hole 8 is formed radially through the bearing part 2 inconnection with the annular groove 4 on the right side in the drawing.The fluid is recirculated to the bearing by fluid recirculator 16, whichis conventional and the exact form of which is known to those skilled inthe art. Further, lands or annular spaces 9, 11 and 12 are formedembracing the rotary shaft 1 in connection with the two annular grooves3 and 4 within the bearing part 2. Land 9 is shown in cross-section inFIG. 2. In this way, the conventional static pressure seal arrangementis accompanied with advantages that the structure is very simple, thereis no need for forming stepped part(s) on the rotary shaft, the rotationof the rotary shaft is much stable and the arrangement can be assembledtogether very simply.

Despite of such advantages, the conventional static pressure sealarrangement is inevitably accompanied by fatal drawbacks as followsalso. In case when it is desired re this arrangement to enhance thesealing effect, the sealing gas pressure inside the annular groove 3(hereinafter referred to as "the in-coming gas annular groove 3") isdesirably made higher than the pressure of the liquid flowing into theannular groove. 4 (hereinafter referred to as "the fluid annular groove4"). As a result of this pressure setting, the sealing gas throttledduring its passage through the land 11 blows into the fluid annulargroove 4 in a highly pressured condition so that it inevitably mixeswith the fluid already dominant within the fluid annular groove 4. Thisinevitable mixing of the sealing gas within the liquid causes increasein the compressibility of the later and the latter is made inferior. Inaddition, under such situation, the fluid discharge hole 8 must allowthe passage of the liquid accompanied with the sealing gas causingincrease in the flow resistance inside the fluid discharge hole 8itself. This increase in the flow resistance naturally inducescorresponding escalation of the pressure inside the fluid annular groove4, thereby resulting in undesirable lowering in the sealing effect ofthe seal arrangement.

A basic embodiment of the static pressure seal arrangement according tothe present invention is shown in FIG. 3, in which elementssubstantially similar to those used in the foregoing arrangement inFIGS. 1 and 2 are shown with similar reference numerals. In addition tosuch known elements, a sealing gas discharge annular groove 101 isformed in the bearing part 2 encircling the rotary shaft 1 at a locationin between the gas annular groove 3 and the fluid annular groove 4. Thisannular groove 101 (hereinafter referred to as "the out-going gasannular groove 101") is communicated to the in-coming gas annular groove3 via the land 11 and to the fluid annular groove 4 via the land 12. Ina radial connection with this out-going gas annular groove 101 there isformed, radially through the bearing part, a sealing gas discharge hole102, whose outlet port is connected to a tank 103 by a piping 104.

Because the out-going gas annular groove 101 is provided in between thein-coming gas annular groove 3 and the fluid annular groove 4, thesealing gas supplied into the in-coming gas annular groove 3 is dividedinto two separate flows; one of the flows spouts outside the bearingpart 2 through the left side land 9 (in the drawing) while preventingundesirable invasion of fluid and dusts or the like into the systemwhile another of the flows blows through the middle land 11 (in thedrawing) for the sealing effect. This part of the sealing gas flows intothe out-going gas annular groove 101. Due to a pressure relationship tothe flowing out fluid, a pressure is generated within the out-going gasannular groove 101 so that the same seals, via the right side (in thedrawing) land 12, the fluid flowing out into the fluid groove 4. Byproper control of the sealing gas pressure by the pressure regulatingvalve 7, flowing-in of the fluid from the right side land 12 into theout-going gas annular groove 101 can be effectively hindered therebypreventing the undesirable mixing of the sealing gas with the liquid,which is the case with the conventional static pressure sealarrangement. When the fluid accidentally flows into the out-going gasannular groove 101, the same mixed with the sealing gas is dischargedtherefrom through the sealing gas discharge hole 102 and is conductedinto the tank 103 via the piping 104. In the tank 103, the sealing gasis separated from the liquid in a sufficiently long period of time and,consequently, the compressibility of the liquid is not increased and theliquid itself is not made inferior too. Further, because the pressureinside the fluid annular groove is not increased, there results noincrease in the flow resistance in the fluid discharge hole 8 causing nolowering in the sealing effect of the seal arrangement.

A modification of the static pressure seal arrangement in FIG. 3 isshown in FIG. 4 in which elements substantially similar to those used inthe foregoing arrangement in FIGS. 1 and 2 are shown and perform thesame functions with similar reference numerals. In the case of thisembodiment, two sets of in-coming gas annular grooves 201 and 202 andtwo sets of out-going gas annular grooves 203 and 204 are arrangedalternately and spacedly from each other along the length of the rotaryshaft 1. The in-coming gas annular grooves 201 and 202 are provided withradially connected sealing gas taker-in holes 206 and 207, respectively.Outlet ports of the sealing gas taker-in holes 206 and 207 arecommunicated to a common given supply source (not shown) of the sealinggas via pressure regulating valves 208 and 209, respectively. Theout-going gas annular grooves 203 and 204 are provided with radiallyconnected sealing gas discharge holes 211 and 212, whose outlets arecommunicated to a common tank 213 via a branched common piping 214. Thefive sets of annular grooves 201, 202, 203, 204 and 4 are communicatedto each other by the lands 9 through 16.

In the case of this arrangement, the direction of the sealing gasflowing into the left side (in the drawing) out-going gas annular groove203 through the land 11 is opposite to that of the sealing gas flowinginto the out-going gas annular groove 203 through the land 12.Consequently, the pressure inside the out-going gas annular groove 203is escalated while this causing the corresponding escalation in the flowspeeds of the sealing gas through the lands 9 and 13. The sealing of thefluid takes place in the land 14.

In the case of this embodiment, when a liquid pressure marked as P inthe drawing is applied to the arrangement, invasion of the liquid intothe arrangement is prevented effectively in the land 9 through which thesealing gas spouts out at the raised flow speed as above mentioned.Consequently, this embodiment is remarkably effective for both insidesealing and outside sealing. Further, proper throttle mechanisms may beused instead of the pressure regulating valves by suitably designing theoperation characteristics of the throttle machanisms.

A further embodiment of the static pressure seal arrangement of thepresent invention is shown in FIGS. 5 and 6. In the case of thisarrangement, a body 301 is placed over a base seat 302 which is providedwith a central liquid hole 303 through which liquid flows out into aland 304 formed in between the confronting faces of the body 301 and thebase seat 302. Along the land 304, there is formed in the upper surfaceof the base seat 302 an in-coming gas groove 306, an out-going gasgroove 307 and an out-going liquid fluid groove 308 reading from theoutside towards the center of the base seat 302. The in-coming gasgroove 306 is communicated to a given supply source (not shown) of thesealing gas via a sealing gas taker-in hole 309 and a pressureregulating valve 311. The out-going gas groove 307 is accompanied with asealing gas discharge hole 312 connected thereto which discharges gasinto the tank 313, while the fluid groove 308 is connected to a fluiddischarge hole 315 for the liquid fluid to flow to the fluidrecirculator 316. All the holes 309, 312 and 315 are formed through thebody of the bace seat 302.

In the case of this embodiment, the liquid flowing out from the centralliquid hole 303 is effectively sealed at a position in the land 304between the out-going gas groove 307 and the fluid groove 308. At thesame time, invasion of the outside dust or the like into the arrangementis effectively prevented by sealing at the position 314 in the land 304.

What is claimed is;
 1. A static pressure seal arrangement for containingliquid between a planar base seat surface and a body overlying butspaced from said surface, said base seat including a liquid intakepassage and a liquid outflow passage nearer the periphery of the baseseat than said intake passage and connecting with a continuous liquidoutlet groove recessed in said base seat surface and totally enclosingan interior area thereof, comprising,at least a continuous inlet sealinggas groove recessed in said base seat surface and totally enclosing aninterior area thereof, at least a continuous sealing gas outlet grooverecessed in said base seat surface, said at least an outlet groove beinglocated interiorally of at least one inlet groove, said at least anoutlet groove also totally enclosing an interior area of said surface,said gas inlet and outlet grooves being located exteriorally of saidliquid outlet groove, a supply passage in said base seat extendingperpendicular and connecting with each gas inlet groove, and an outputpassage in said base seat extending perpendicular and connecting witheach gas outlet groove.